This application is based on Japanese Patent Applications No. 2001-241308 filed on Aug. 8, 2001, and No. 2002-110124 filed on Apr. 12, 2002, the disclosure of which is incorporated herein by reference.
The present invention relates to a heat exchanger used for a refrigerant cycle for a vehicle or a home, for example. More particularly, the present invention relates to a structure for improving a heat exchange between a first fluid flowing inside tubes and a second fluid flowing outside the tubes in a laminated-type heat exchanger.
In a laminated-type heat exchanger used for a condenser of a refrigerant cycle of an air conditioner, as shown in FIG. 13, a heat-exchanging portion is constructed by plural fins 101 and tubes 103. In addition, two headers are provided to be connected to one end and the other end of the tubes 103, respectively, to communicate with the tubes 103. However, because louvers 104 are provided in the fins 101 for facilitating a heat exchange with air while each outer wall surface of the tubes 103 is formed into a flat surface, heat-transmitting performance on the air side is not sufficiently improved.
On the other hand, in a heat exchanger described in JP-A-2000-161896, as shown in FIGS. 14A and 14B, protrusion portions 108 or dimple portions 105 (recesses) are provided in each outer wall surface of tubes 103 having end portions inserted into insertion holes 107 of a header 106. However, the protrusion portions 108 or the dimple portions 105 become a dead region relative to a flow of air, and air does not flow through the dead region. Accordingly, the protrusion portions 108 or the dimple portions 105 are not used for improving the heat-transmitting performance on the air side.
In view of the foregoing problems, it is an object of the present invention to provide a heat exchanger having a plurality of tubes for performing a heat exchange between a first fluid flowing inside the tubes and a second fluid flowing outside the tubes, which effectively improves heat-transmitting performance on a side of the second fluid.
According to the present invention, a heat exchanger includes a plurality of flat tubes disposed for performing a heat exchange between a first fluid flowing inside the tubes and a second fluid flowing outside the tubes, and a plurality of heat transmitting members for increasing a heat-exchanging efficiency between the first fluid and the second fluid. Each of the heat-transmitting members is disposed between adjacent tubes, and has contact portions contacting an outer wall surface of each tube adjacent to each heat transmitting member. In the heat exchanger, each of the tubes has a plurality of protrusion portions protruding from the outer wall surface of each tube toward the heat transmitting members to define a fluid passage at least between adjacent protrusion portions or around the protrusion portions such that the second fluid passes through the fluid passage between adjacent protrusion portions. Accordingly, the second fluid flowing through the fluid passage is also used for performing the heat exchange with the first fluid flowing inside the tubes, heat-transmitting performance on the second fluid side can be improved.
Preferably, the fluid passage is provided between the outer wall surface of each tube and the contact portions of each heat-transmitting member, and is constructed by at least groove-shaped recess portions between adjacent protrusion portions or around the protrusion portions. Therefore, the second fluid readily passes through the recess portions without staying in the recess portions. In addition, the fluid passage has at least one side opening between inlet side openings for introducing the second fluid into the recess portions and outlet side openings for allowing the second fluid to flow out from the recess portions, the inlet side openings are provided at an upstream end of each tube in a flow direction of the second fluid, and the outlet side openings are provided at a downstream end of each tube in the flow direction of the second fluid. Accordingly, the second fluid readily passes through the recess portions on the outer wall surface of each tube while effectively performing a heat exchange with the first fluid. When both the inlet side openings and the outlet side openings are provided, the second fluid is introduced into the recess portions through the inlet side openings, and thereafter, flows out from the recess portions through the outlet side openings. Therefore, in this case, the second fluid further effectively flows through the recess portions, and heat-transmitting performance on the second fluid side can be effectively improved.
Alternatively, according to a heat exchanger of the present invention, the fluid passage through which the second fluid flows can be provided in intermediate plates each of which is disposed adjacent the tube and the heat transmitting member. Because the fluid passage is provided in each of the intermediate plates contacting flat outer wall surfaces of flat tubes, the second fluid flowing through the fluid passage is also heat-exchanged with refrigerant flowing inside the tubes, and heat-transmitting performance on the second fluid side can be improved. Even in this case, the fluid passage can be constructed by a plurality of recess portions recessed in a plate thickness direction of each intermediate plate, and the fluid passage has at least one side opening between inlet side openings from which the second fluid flows into the recess portions, and outlet side openings from which the second fluid flows out from the recess portions. Accordingly, in the heat exchanger, the second fluid readily flows through the recess portions provided in the intermediate plates, and heat-exchanging efficiency on the second fluid side can be further improved.